Dyno results hot off the presses!

[pggg]

Main jets probably too big on that last one. Wonder what numbers would come up irunning big jets and no filters.

[Shuriken]

I gotta say I like the flat and predictable lines of the 4-2.

My 79sf didn't have any muffs on it when I got it so I abandoned the 4-2 idea. I like the looks of the 4-1, the sound of the 4-1, but maybe in looking at all these 4-1 results, I don't like the dip.

I think it says a lot for factory engineering. The 4-2 factory exhaust does a good job, IMO.

That said, if I could iron out the midrange in mine, it feels very fast on the top end, the midrange just seems to crap out. The bike is stock except for the 4-1.

Ben

[Pat Kelly]

I thought that was the main difference between 4 into 1 and 4 into 2.
4>1 enchances top-end performance (horsepower) at the sacrifice of less mid or low range performance.
4>2 works better in the mid-rance (torque), particularlt with the balance tube between the mufflers.
I was looking at a Triumph triple and noticed it had balance tubes at the downtubes just below where they bolt on the head.

I don't know if anyone noticed my thread on this gauge set-up
www.veypor.com
Have your own custom dyno. I like the HUD option.

[81xsproject]

I saw a setup at Napa the other day that was made to run on a PDA. It was advertised as a "dyno" but it didn't have anything about fuel mixture that I could tell. I don't see how it could work. Does it do calculations based on tire diameter vs rpm vs speed?

[GNEPIG]

.. this guy Jeremy Sells sounds like a real carb Guru.. i hope he still has his XS11s
.. here we have the dip at 5 grand with the 4/1 again.
now these are great numbers!

[pggg]

Numbers mean nothing on different dynos that 90 hp might only be 80 hp. GNE must be an expert at setting up a dyno. Peak torque at 4000 doesn't seem right, it should run flat thru to 6000 - 7000. Also a good 4-1 boosts performance right across the range even at 2000 - 5000.

[MAXIMAN]

So that's a dyno run of someone elses bike in 2003?

Who's bike is it? What bike is it? What are the mods?

[xs650mike]

Whatever it was it was shut off before it got to 8 grand even.

[GNEPIG]

.. i thought that was a little strange that the big hump was on the wrong side of 5 grand also but i'm still new at this

click on the search option at the top of the orange strip to the left of the page then type in the word dyno then look for a post by Jeremy Sells.. tells all about it

.. looks like it was over by 8000rpms Mike, not much use in going much farther i guess

[81xsproject]

In case anyone wants to read that post, here it is

[GNEPIG]

.. this is the other pic from Jeremy, its a combo of three different runs.. after changes obviously

[Jeremy_Sells]

Been a long time...

What a surprise to pop on here and see my post still floating around. I havent done much to the XS since then, except ride it and it has been performing awesome! I recently picked up a 1198 bigbore kit and that is the next addition coming soon (before the days get warmer again). With your logic pggg, that 90hp could also mean 100! Why only error to a lesser #? Those tests were done on the same Dynojet dyno, calibrated on every run to standard sea level temp and baro. pressure. The tech spent 1 week in Las Vegas at dynojet's HQ learning how to run the dyno and his race team took 4th place in the National pro-thunder series a few years back with a Ducati 749. With each modification, three consecutive runs were made for consistency and the best possible accuracy.

Maximan - my bike is a 79SF with a Jardine 4-1, and drilled out airbox, stock main jets, one size smaller pilots.

This years goal with the big-bore is to work towards 100 wheel HP! I plan to start with the big bore (1198) and see what gains come from that. A set of cams from Webcams would follow and in the long term - some head porting done here in Portland by Dan Baisley of Baisley High Performance. These bikes are amazing and my goal with my XS has always been to make methodical mods and test everything for power gains and compatibility. I would love to answer any questions about what I did to get these #'s and share my experiences in tuning for power, reliability and economy. I don't get much of a chance to hang out here on the forum but I will try to follow up on here every few days. You can always drop me a line at jlsells@gmail.com as well.

Cheers -

[pggg]

Chances are better than average that it's less. If stuck with the puny restrictive 34mm CV carbs it won't get much higher. 120 h.p. at the 130 tyre, I wouldn't gas it mid-corner. Wouldn't be much good for accelerating out of corners on a lean.

[Jeremy_Sells]

This is fun… What good is science without debate?  I have spent several years working with dynos tuning cars and bikes and have a pretty good grasp on how useful they can be as a tuning tool. I work at ipd (www.ipdusa.com) and I use dynos all the time to test performance and reliability on parts for our Volvo and Subaru product lines. We build some cool stuff and often a dyno is the only way to ensure compatibility with an engine management system. Knowing how to use one is a heck of a lot more important than making more power than the other guy and in a competetive niche market like I’m in, being able to support your products with proven results is key to maintaining our 40+ year reputation. By the way, here is a link to our latest cool project car for SEMA: http://www.swedespeed.com/news/publi...ticle_678.html

Those who use dynos to test results know that without a non-modified, baseline run, modified results carry little weight. Without a baseline, there is no way to determine net gains or losses and there is no way to compare numbers with others on different dynos. What makes my results notable is that like a lot of us on here, I used the same dyno for all of the tests. When my bike was dead stock, down to the air filter, it put down 78 WHP (wheel horse power). Considering that Yamaha claimed a little over 90 at the crank, my number would indicate a 16% parasitic drive train loss which would be darn close for a shaft driven machine. After the initial run, it took me over a year to get the parts together and arrange for an afternoon block of dyno time. My first “modified” run was just with the 4-1 and I saw a gain and a mixture change. I changed my airbox to an open style and did 3 more pulls. I went away with obvious gains and ordered some different primary jets to dial everything in. My last run on the dyno, I was able to produce 90.5 hp and 69.1 torque. Now, because I had performed a baseline run first, I could compare my results and come up with some theories on the gains that were achieved and how the bike responded to the mods. Forgetting the end results and any final numbers, no one can deny that I saw a gain of 12 hp and 9 lb/ft of torque which works out to a 16% power gain equaling out to 107 hp at the crank considering the parasitic drive train loss determined earlier. Looking at everybody else’s #’s, those of us with close to the same mods are all seeing a 15-17% gain, where the beginning and endings numbers fall may indicate a small difference in dynos, but nonetheless – we are all seeing and feeling our bikes getting faster and running better.

Looking at the charts that we have all posted it is obvious that the computer program that each shop uses produces a different looking chart with varying scales on the X and Y lines. Although my torque curve looks to have an unusual and significant dip, by referencing the Y scale, it doesn’t change much more than 3-4 lb/ft throughout the pull – pretty flat and consistent just like it should be.

I love these bikes, they are easy to tune and respond well to the common mods and I have spent many hours and $100’s of dollars to get my bike to where I like it. Pggg, it would be cool if you ran down to one of these shops (http://www.dynojet.com/maps/bikedynos/newzealand.htm) and posted your results here as well. The more data that we can pull together here on this forum, the better off all of our favorite bikes will be!

Have fun all -

[pggg]

Damn I'd like to but they're all rip-offs round here. Last I heard was $150 and all you get is 5 minutes and lots of unanswered questions Backroads my dyno but hopefully I'll get a dyno run someday.